Index: lib/Target/RISCV/CMakeLists.txt
===================================================================
--- lib/Target/RISCV/CMakeLists.txt
+++ lib/Target/RISCV/CMakeLists.txt
@@ -4,6 +4,7 @@
 tablegen(LLVM RISCVGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM RISCVGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM RISCVGenAsmMatcher.inc -gen-asm-matcher)
+tablegen(LLVM RISCVGenAsmWriter.inc -gen-asm-writer)
 
 add_public_tablegen_target(RISCVCommonTableGen)
 
@@ -12,5 +13,6 @@
   )
 
 add_subdirectory(AsmParser)
-add_subdirectory(TargetInfo)
+add_subdirectory(InstPrinter)
 add_subdirectory(MCTargetDesc)
+add_subdirectory(TargetInfo)
Index: lib/Target/RISCV/InstPrinter/CMakeLists.txt
===================================================================
--- /dev/null
+++ lib/Target/RISCV/InstPrinter/CMakeLists.txt
@@ -0,0 +1,3 @@
+add_llvm_library(LLVMRISCVAsmPrinter
+  RISCVInstPrinter.cpp
+  )
Index: lib/Target/RISCV/InstPrinter/LLVMBuild.txt
===================================================================
--- /dev/null
+++ lib/Target/RISCV/InstPrinter/LLVMBuild.txt
@@ -0,0 +1,23 @@
+;===- ./lib/Target/RISCV/InstPrinter/LLVMBuild.txt -------------*- Conf -*--===;
+;
+;                     The LLVM Compiler Infrastructure
+;
+; This file is distributed under the University of Illinois Open Source
+; License. See LICENSE.TXT for details.
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[component_0]
+type = Library
+name = RISCVAsmPrinter
+parent = RISCV
+required_libraries = MC Support
+add_to_library_groups = RISCV
Index: lib/Target/RISCV/InstPrinter/RISCVInstPrinter.h
===================================================================
--- /dev/null
+++ lib/Target/RISCV/InstPrinter/RISCVInstPrinter.h
@@ -0,0 +1,43 @@
+//===-- RISCVInstPrinter.h - Convert RISCV MCInst to asm syntax ---*- C++ -*--//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class prints a RISCV MCInst to a .s file.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_RISCV_INSTPRINTER_RISCVINSTPRINTER_H
+#define LLVM_LIB_TARGET_RISCV_INSTPRINTER_RISCVINSTPRINTER_H
+
+#include "MCTargetDesc/RISCVMCTargetDesc.h"
+#include "llvm/MC/MCInstPrinter.h"
+
+namespace llvm {
+class MCOperand;
+
+class RISCVInstPrinter : public MCInstPrinter {
+public:
+  RISCVInstPrinter(const MCAsmInfo &MAI, const MCInstrInfo &MII,
+                   const MCRegisterInfo &MRI)
+      : MCInstPrinter(MAI, MII, MRI) {}
+
+  void printInst(const MCInst *MI, raw_ostream &O, StringRef Annot,
+                 const MCSubtargetInfo &STI) override;
+  void printRegName(raw_ostream &O, unsigned RegNo) const override;
+
+  void printOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O,
+                    const char *Modifier = nullptr);
+
+  // Autogenerated by tblgen.
+  void printInstruction(const MCInst *MI, raw_ostream &O);
+  static const char *getRegisterName(unsigned RegNo,
+                                     unsigned AltIdx = RISCV::ABIRegAltName);
+};
+}
+
+#endif
Index: lib/Target/RISCV/InstPrinter/RISCVInstPrinter.cpp
===================================================================
--- /dev/null
+++ lib/Target/RISCV/InstPrinter/RISCVInstPrinter.cpp
@@ -0,0 +1,55 @@
+//===-- RISCVInstPrinter.cpp - Convert RISCV MCInst to asm syntax ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class prints an RISCV MCInst to a .s file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RISCVInstPrinter.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FormattedStream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "asm-printer"
+
+// Include the auto-generated portion of the assembly writer.
+#include "RISCVGenAsmWriter.inc"
+
+void RISCVInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
+                                 StringRef Annot, const MCSubtargetInfo &STI) {
+  printInstruction(MI, O);
+  printAnnotation(O, Annot);
+}
+
+void RISCVInstPrinter::printRegName(raw_ostream &O, unsigned RegNo) const {
+  O << getRegisterName(RegNo);
+}
+
+void RISCVInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
+                                  raw_ostream &O, const char *Modifier) {
+  assert((Modifier == 0 || Modifier[0] == 0) && "No modifiers supported");
+  const MCOperand &MO = MI->getOperand(OpNo);
+
+  if (MO.isReg()) {
+    O << getRegisterName(MO.getReg());
+    return;
+  }
+
+  if (MO.isImm()) {
+    O << MO.getImm();
+    return;
+  }
+
+  assert(MO.isExpr() && "Unknown operand kind in printOperand");
+  MO.getExpr()->print(O, &MAI);
+}
Index: lib/Target/RISCV/LLVMBuild.txt
===================================================================
--- lib/Target/RISCV/LLVMBuild.txt
+++ lib/Target/RISCV/LLVMBuild.txt
@@ -16,17 +16,18 @@
 ;===------------------------------------------------------------------------===;
 
 [common]
-subdirectories = AsmParser TargetInfo MCTargetDesc
+subdirectories = AsmParser InstPrinter TargetInfo MCTargetDesc
 
 [component_0]
 type = TargetGroup
 name = RISCV
 parent = Target
 has_asmparser = 1
+has_asmprinter = 1
 
 [component_1]
 type = Library
 name = RISCVCodeGen
 parent = RISCV
-required_libraries = Core CodeGen RISCVInfo Support Target
+required_libraries = AsmPrinter Core CodeGen MC RISCVAsmPrinter RISCVDesc RISCVInfo Support Target
 add_to_library_groups = RISCV
Index: lib/Target/RISCV/MCTargetDesc/LLVMBuild.txt
===================================================================
--- lib/Target/RISCV/MCTargetDesc/LLVMBuild.txt
+++ lib/Target/RISCV/MCTargetDesc/LLVMBuild.txt
@@ -19,5 +19,5 @@
 type = Library
 name = RISCVDesc
 parent = RISCV
-required_libraries = MC RISCVInfo Support
+required_libraries = MC RISCVAsmPrinter RISCVInfo Support
 add_to_library_groups = RISCV
Index: lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
===================================================================
--- lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
+++ lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
@@ -13,6 +13,7 @@
 
 #include "RISCVMCTargetDesc.h"
 #include "RISCVMCAsmInfo.h"
+#include "InstPrinter/RISCVInstPrinter.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCInstrInfo.h"
@@ -48,6 +49,14 @@
   return MAI;
 }
 
+static MCInstPrinter *createRISCVMCInstPrinter(const Triple &T,
+                                               unsigned SyntaxVariant,
+                                               const MCAsmInfo &MAI,
+                                               const MCInstrInfo &MII,
+                                               const MCRegisterInfo &MRI) {
+  return new RISCVInstPrinter(MAI, MII, MRI);
+}
+
 extern "C" void LLVMInitializeRISCVTargetMC() {
   for (Target *T : {&TheRISCV32Target, &TheRISCV64Target}) {
     RegisterMCAsmInfoFn X(*T, createRISCVMCAsmInfo);
@@ -55,5 +64,6 @@
     TargetRegistry::RegisterMCRegInfo(*T, createRISCVMCRegisterInfo);
     TargetRegistry::RegisterMCAsmBackend(*T, createRISCVAsmBackend);
     TargetRegistry::RegisterMCCodeEmitter(*T, createRISCVMCCodeEmitter);
+    TargetRegistry::RegisterMCInstPrinter(*T, createRISCVMCInstPrinter);
   }
 }
Index: test/MC/RISCV/lit.local.cfg
===================================================================
--- /dev/null
+++ test/MC/RISCV/lit.local.cfg
@@ -0,0 +1,3 @@
+if not 'RISCV' in config.root.targets:
+    config.unsupported = True
+
Index: test/MC/RISCV/rv32i-invalid.s
===================================================================
--- /dev/null
+++ test/MC/RISCV/rv32i-invalid.s
@@ -0,0 +1,30 @@
+# RUN: not llvm-mc -triple riscv32 < %s 2>&1 | FileCheck %s
+
+# Out of range immediates
+ori a0, a1, -2049 # CHECK: :[[@LINE]]:13: error: immediate must be an integer in the range [-2048, 2047]
+andi ra, sp, 2048 # CHECK: :[[@LINE]]:14: error: immediate must be an integer in the range [-2048, 2047]
+
+# Invalid mnemonics
+subs t0, t2, t1 # CHECK: :[[@LINE]]:1: error: unrecognized instruction mnemonic
+nandi t0, zero, 0 # CHECK: :[[@LINE]]:1: error: unrecognized instruction mnemonic
+
+# Invalid register names
+addi foo, sp, 10 # CHECK: :[[@LINE]]:6: error: unknown operand
+slti a10, a2, 0x20 # CHECK: :[[@LINE]]:6: error: unknown operand
+slt x32, s0, s0 # CHECK: :[[@LINE]]:5: error: unknown operand
+
+# RV64I mnemonics
+addiw a0, sp, 100 # CHECK: :[[@LINE]]:1: error: unrecognized instruction mnemonic
+sraw t0, s2, zero # CHECK: :[[@LINE]]:1: error: unrecognized instruction mnemonic
+
+# Invalid operand types
+xori sp, 22, 220 # CHECK: :[[@LINE]]:10: error: invalid operand for instruction
+sub t0, t2, 1 # CHECK: :[[@LINE]]:13: error: invalid operand for instruction
+
+# Too many operands
+add ra, zero, zero, zero # CHECK: :[[@LINE]]:21: error: invalid operand for instruction
+sltiu s2, s3, 0x50, 0x60 # CHECK: :[[@LINE]]:21: error: invalid operand for instruction
+
+# Too few operands
+ori a0, a1 # CHECK: :[[@LINE]]:1: error: too few operands for instruction
+xor s2, s2 # CHECK: :[[@LINE]]:1: error: too few operands for instruction
Index: test/MC/RISCV/rv32i-valid.s
===================================================================
--- /dev/null
+++ test/MC/RISCV/rv32i-valid.s
@@ -0,0 +1,23 @@
+# RUN: llvm-mc %s -triple=riscv32 -show-encoding | FileCheck %s
+# RUN: llvm-mc %s -triple=riscv64 -show-encoding | FileCheck %s
+
+addi ra, sp, 2 # CHECK: encoding: [0x93,0x00,0x21,0x00]
+slti a0, a2, -20 # CHECK: encoding: [0x13,0x25,0xc6,0xfe]
+sltiu s2, s3, 0x50 # CHECK: encoding: [0x13,0xb9,0x09,0x05]
+xori tp, t1, -99 # CHECK: encoding: [0x13,0x42,0xd3,0xf9]
+ori a0, a1, -2048 # CHECK: encoding: [0x13,0xe5,0x05,0x80]
+andi ra, sp, 2047 # CHECK: encoding: [0x93,0x70,0xf1,0x7f]
+andi x1, x2, 2047 # CHECK: encoding: [0x93,0x70,0xf1,0x7f]
+
+add ra, zero, zero # CHECK: encoding: [0xb3,0x00,0x00,0x00]
+add x1, x0, x0 # CHECK: encoding: [0xb3,0x00,0x00,0x00]
+sub t0, t2, t1 # CHECK: encoding: [0xb3,0x82,0x63,0x40]
+sll a5, a4, a3 # CHECK: encoding: [0xb3,0x17,0xd7,0x00]
+slt s0, s0, s0 # CHECK: encoding: [0x33,0x24,0x84,0x00]
+sltu gp, a0, a1 # CHECK: encoding: [0xb3,0x31,0xb5,0x00]
+xor s2, s2, s8 # CHECK: encoding: [0x33,0x49,0x89,0x01]
+xor x18, x18, x24 # CHECK: encoding: [0x33,0x49,0x89,0x01]
+srl a0, s0, t0 # CHECK: encoding: [0x33,0x55,0x54,0x00]
+sra t0, s2, zero # CHECK: encoding: [0xb3,0x52,0x09,0x40]
+or s10, t1, ra # CHECK: encoding: [0x33,0x6d,0x13,0x00]
+and a0, s2, s3 # CHECK: encoding: [0x33,0x75,0x39,0x01]